Method of manufacturing split rings



Patented Jan. 8, 1929.

ARDEN JOHN MUMMERT, 0F UNIVERSITY CITY, MISSOURI, ASSIGNOR TO 'MCQUAY-V NORRIS MANUFACTURING COMPANY, OF ST. LOUIS, MISSOURI, A CORPORATION OF DELAWARE.

. vMETHOD OF MANUFACTURING SPLIT RINGS.

Application filed March 6, 1926. Serial No. 92,789.

,My invention relates to methods of manufacturing split rings and more particularly to methods of manufacturing-resilient split rings such as are used on the reciprocating pistons of internal combustion engines, air compressors, steam 'engines and other like devices.

In the manufacture of such rings it is desirable that the rings when finished and placed on a piston shall have uniform radial pressure outwardly against the wall ofthe cylinder in which the piston reciprocates. In order to produce rings which in use will have an equal radial pressure the rings have lbeen formed so that when open they have an outof-round shape and `when compressed into closed position in a cylinder they are substantially circular and the stress throughout the closed ring is such that there is a resultant approximately uniform radial pressure upon the cylinder wall. In some instances the rings were machined to this out-of-round shape while in other instances the rings were individually cast from patterns which follow the proper out-of-round curve and which determine the out-of-round shape of the cast rings.

The casting of individual rings is the preferred method and in making the molds for these castings from an out-of-round pattern, the molding sand packs much firmer on the inside of the pattern than it does on the outside and, therefore, the innersurface of the casting madev from one of these molds is smoother and truer to the pattern than the outer surface.

The cast rings areof larger diameter than the finished rings to be produced so that a section of the unfinished ring may be cut out to allow the finished ring to be compressed in a'cylinder and to give it the proper resiliene-y to press uniformly outwardly against the cylinder wall. The rings after they are removed from the molds are first roughly ground on their inner and outer faces to re' v move any projections or burrs and after this rough grinding has been completed thesides of each ring are ground and then machined until the ring is of the desired finished width. The ring is then split and a section of the ring substantially equal to the above de'- scribed difference in the sizes of the cast ring andthe nished ring is removed.

The next and final step in the manufacture of the ring is the finishing of the outer face thereof. The rings to be finished must be brought into closed position, that is, the position which they normally'assume when compressed for use in a cylinder. In the method of finishing the outer face of the ring heretofore used, the rings are brought into closed p osition by compressing a plurality of the rlngs in `a cylindrical jig,.the ,diameter of which is, with the exception of. an allowance for the metal to be removed in finishing, the lsame as the diameter. ofthe cylinder in which the rings will be used when finished. A mandrel is placed through the nest. of rings in the cylindrical jig, end plates are placed at each end of the nest and heavy nuts threaded on the mandrel bar are turned down to clamp the rings sideways between the end plates, thereby holding the rings in closed position. The cylin'drical jig is then removed and the mandrel is placed in a proper machine for grinding or turning whereby the outer faces of the rings are finished. However, this method of finishing the outer faces of the ring allows inac curacies and irregularities in the thickness of the rings, because, as stated above, the rough outer face of a cast ring, even after being roughly ground as described, is much more likely to be untrue and to contain irregularities than the inner face of the ring, and these l irregularities contacting with the cylindrical j ig often cause the unfinished rings to be com` pressed to different degrees, and, hence, in

'the finishing different amounts of metal will be removed from different rings or from different points on the same ring.

The object of my invention is to provide a method of manufacturing resilient split rings and more particularly to provide a method of finishing the outer faces of such rings which will insure accurate finishing of the rings more nearly to a desired uniform thickness and thereby tend to create amore uniform radial pressure of the rings when in closed position in a cylinder.

My new and improved method of manufacturing split rings does not differ from the method as now practiced in respect to the rough grinding of the inner and outer faces, the finishing kof the sides, or the splittin of the rings, as heretofore described, but oes differ in the way the rings are-brought into as described above, is more true than the outer face, my improved method assures a more uniform ring thickness which'tends to create a more uniform ,radial pressure when the ring is in use in a cylinder.

One of the many forms of device whic may be used in the practice of my new and f' improved method is fully shown in the accompanying drawings wherein similar let ters are used to designate similar parts: Fig.

is a cross section of a mandrel showing a ring in open position thereon: Fig. 2 is a cross section of a mandrel with a ring in closed position; Fig. 3 is a vertical section of the device; and Fig. 4 shows the mandrel and a plurality of rings secured in closed position. In order that my new and improved method as will yhereinafter be described may be more easily understood I will first describe the deviceo shown in the drawings.

Referring to the figures, the mandrel shown in Figs.3 ande thereof has the body portion A with'the shanks lB and D eX- tending outwardly from each end thereof. The end of the body 'portion A nearest the shank B is enlarged to form al sho'ulder C. The shankl) is adapted to pass through the collar E and is threaded to receive the nut F whereby the rings are clamped or held togetherfon the enlarged portion A' of the mandrel. The spool J having thereon the coil K is provided with a hollow center adapted to receive the shank B and the top of the spool has therein a recess adapted to receive the enlarged portion of the body portion A of the mandrel. The switch L is provided to control the flow of electricity, from a source of sup ly not shown, through the coil K. The pin hole N in the wall ofthe recess of the .spooll J and through the hole P in. the mandrel whereby the mandrel may be maintained in fixed position and be revented from turning in the spool when t e nut F is tightened for the purpose hereinafter explained.y

The practice of my new and improved method with the device shown in the drawings and described above is as follows: The mandrel is positioned with the shank B eX tending into the hollow interior ofthe spool J, as shown in Fig. 3. One or moresplit may be inserted through the a length suiiicient to accommodate a substantial number of the rings. The rings are open and are positioned around the bod portion A as shown in Fig. l. The lower side of the bottom ring rests on the shoulder C and the upper side of the top ring is above/che top of the body portion A of the mandrel, as shown in Fig. 3. The collar E is placed over the shank B and the nut F is placed on the shank D and is screwed down until it bears lightly against the upper surface of the collar E. Electricity is then passed through the coil K by closing the switch L therebyy causing an electro-magnetic action whereby the mandrel is magnetized to cause the rings H to be brought simultaneously linto closed position on the body portion A. The nut F is then turned down to clamp the rings I-I bey tween the collar E and the shoulder C whereby the rings are held in closed position on the mandrel. The pin M extending through the holes N and Pprevents the mandrel from rotating when the nut F is being turned down. After the rings have been secured in" closed position, as described, the switch L is opened thereby stopping the flow of electricity through the coil K and thereby demagnetizmg the mandrel. The pin M is then withdrawn and the mandrel is removed from the spool J and placed in a lathe or other suitable finishing machine. f

Ivprefer that when the rings are brought into closed position the ends thereof will not be caused to butt, but will be separated a slight distance, as shown in Fig. 2, and I, therefore, use a mandrel the body portion A of which has' a circumference slightly greater than the bore of a ring when in closed position with the ends not in contact. Ifsuch aj mandrel is not used, and theends of therings are allowedto butt, the circumference of the ring might bey distorted under a continued application of a force tending to close the rings, .and if the rings are machined while so distorted, different' amounts of vmetal would be removed from the ring at different point-,sin its periphery, and the ring would thennot be of uniform thickness.

This application is directed to a method to accomplish the objects set forthabove and for the sake of clarity only one form of device for creating magnetic force has been shown and described, however, it may be readily un# derstood that the device described above in connect-ion with'the practice of my method is only one of the many forms of devices which may be provided to apply magnetic force sufplurality of said rings on a' mandrel, applying magnetic force from Within said rings to cause said rings to be brought simultaneously into closedposition, and then placing said mandrel in a finishing machine and operating on said rings while held in closed position. A

2. A method of finishing the outer faces of split rings which includes placing a plurality of said rings on a mandrel, applying magnetic force to cause said rings to be brought simultaneously into closed position on said mandrel, holding said rings in closed position, discontinuing the application of said magnetic force, and then placing said mandrel in a finishing machine.

3. A method of finishing the outer faces of resilient split rings which includes lacing a plurality of said rings on a mandre magnetizing said mandrel to cause said rings to bev brought simultaneously into closed position, and then placing said mandrel in a finishing machine and operating on said rings.

4. A method of finishing the outer face of a split ring which includes placing said ring on a mandrel, magnetizing said mandrel to cause said ring to be brought into closed position, holding said ring in closed position, and then finishing the outer face of said ring.

5. A method of finishing the outer faces of resilient split rings which includes placing one or more of said ringson a mandrel, magnetizing said mandrel to cause said rings to,

be brought simultaneously into closed position, holding said rings in closed position on said mandrel, demagnetiaing said mandrel,

and then finishing the outer faces of said rings.

6. A method of finishing the outer faces of resilient split rings which includes placing one or more of saidrings on a mandrel whose circumference isslightly greater than that` of the bore of said rings when closed with the ends .thereof in contact, magnetizing said mandrel to' cause said rings to be brought into closed position, holding said rings in closed position, and then finishing the outer faces of said rings.

7.. A method of manufacturing a piston ring which includes casting a ring, finishing vthe sides of said ring, splitting saidring,

placing said ring on a mandrel, applying magnetic force to cause said ring to be brought 1nto closed position, holding said ring in .closed position and then finishing the outer faceof said ring.

8. A method of manufacturing a piston ring which includes casting an out-of-round ring, finishing the sides of saidring, splittin said ring and removing a section thereo placing said ring on a mandrel, magnetizing said mandrel to cause said ring to be brought into closed position, holding said ring in closed position, and then finishing the outer face of said ring.

9. A method of manufacturing resilientv piston rings which includes casting a'A plurality of out-of-round rings'slightly larger than the size of rings to be manufactured, finishing the sides of said rings, splitting said rings and removing a section from each thereof substantially equal to the difference in size between said cast rings and the rings when finished, placing said rings on a mandrel, magnetizing said mandrel to cause said rings to be brought simultaneously into closed position, holding said rings in closed position, demagnetizing said mandrel, and then placing said mandrel in a finishing machine and operating on said rings. v

In witness whereof I have signed my name to the foregoing specification. v

ARDEN JOHN MUMMERT. 

